Lightening is not actually a spell that can be 'resisted' as it does direct element damage, that damage power is then filtered by your rating in Energy Resistance(armour rating)
Train Resisting Spells by using:
Clumsy
Weaken
Curse
Mana Vampire
Poison
Feeblemind
Paralyze
These spells should get you gains, as their effectiveness does come back to the players level in Magic Resistance, this can be easily observed by duration of spell also how heavily a curse type is applied.
Try these, and you should be fine!
Thanks for posting about your issue, I hope this helps!